This revision addresses the few remaining comments and suggestions made by the previous Committee. Pre-frontal deficits have been hypothesized to be central to schizophrenia. A pilot Magnetic Resonance Imaging (MRI) study conducted by the applicant provides initial support for reduced pre-frontal area and pre-frontal functional deficits in schizophrenics as well as in "normal" subjects with schizotypal features. The main aim of this study is to provide pilot data on (l) whether unmedicated, un-institutionalized subjects diagnosed with schizotypal personality disorder (SPD) drawn from the community, compared to normals, show the functional neuropsychological frontal processing abnormalities previously found in medicated schizophrenics. (2) whether MRI structural pre-frontal deficits found in schizophrenics and subjects with schizotypal traits in a previous pilot study can be replicated in a larger sample of diagnosed, unmedicated community schizotypals. Hypotheses will be tested using 26 subjects diagnosed with schizotypal personality disorder and 26 normal controls matched on sex and ethnicity. Neuropsychological tasks with a frontal loading to be utilized in the present study will include the Continuous Performance Task, Wisconsin Card Sorting Task, and Verbal Fluency test. Magnetic resonance imaging (MRI) using three-dimensional volumetric measurement will be used to assess prefrontal volume, separately measuring grey and white matter. Findings of this study will help to assess whether prefrontal deficits are relatively central to schizophrenia in that they are also observed in unmedicated subjects with the schizophrenia-spectrum disorder of schizotypal personality. This study will allow the applicant to develop further expertise in the new MRl techniques proposed and help establish reliability data for these measures. This in turn will facilitate the study's long-term programmatic aims which are to (a) test the above hypotheses on larger samples of schizotypals and schizophrenics, (b) assess the relative specificity of findings by testing patients with bipolar disorders, and (c) store the MRI to tape for future measurement of other regions.